Apparatuses for erasing a storage phosphor layer with a radiation source for producing and emitting erasing radiation are used in particular in the field of computer radiography (CR) for medical purposes.
The apparatuses are used to produce a picture of an object, for example a patient or a body part of the patient, by means of X-ray radiation. The picture is stored in a storage phosphor layer as a latent picture. Therefore, this type of X-ray picture contains X-ray information about the object. In order to read out the X-ray information stored in the storage phosphor layer, the storage phosphor layer is stimulated by means of an irradiation device. As a result of this stimulation the storage phosphor layer emits radiation, which has an intensity corresponding to the X-ray information stored in the storage phosphor layer. The radiation emitted by the storage phosphor layer is collected by a detection device and converted into electrical signals, which contain an image of the X-ray information. The electrical signals are further processed and the X-ray information stored in the storage phosphor layer is then made visible. The X-ray information can be displayed directly on a monitor, for example, or be written onto a photographic X-ray film by means of a printer used especially for X-ray pictures.
After reading out the X-ray information from the storage phosphor layer, remains of the latent picture remain in the latter. Furthermore, noise information can be stored in the layer. In order to be able to use the storage phosphor layer for further X-rays, it is important erase this information. For this procedure, a radiation source is used that emits erasing radiation onto the storage phosphor layer. An apparatus for erasing a storage phosphor layer is known from U.S. Pat. No. 7,075,200 B2. As a radiation source, this erasing apparatus contains two lines with light emitting diodes, disposed parallel to one another, for emitting the erasing radiation. For erasure, the storage phosphor layer is pushed in a direction of conveyance through a ray path of the lines of light emitting diodes. The two lines of light emitting diodes are integrated with reflectors which are spaced apart from one another. The reflectors serve to reflect erasing radiation emitted by the light emitting diodes in the direction of the storage phosphor layer. The reflectors have a groove-shaped cross-sectional surface with obtuse inner angles so that the groove-shaped profile of the reflectors opens from the light emitting diode arrangement in the direction of the storage phosphor layer. The width of the reflectors here in the direction of conveyance is adapted to their function of guiding the radiation of the erasing radiation emitted by the light emitting diodes.